#include <string.h>
#include <iostream>
#include <string>

using namespace std;
using std::string;

int main()
{
    string str("hello");
    cout << "str:" << str << endl;
    cout << "is str empty:" << str.empty()<< endl;
    cout << "str'size ：" << str.size()<< endl;
    cout << "str'length:" << str.length() << endl;

    str.push_back('!');
    cout << "str:" << str << endl;

    size_t pos = str.find('e');
    cout << pos << endl;

    string str2("lly");
    cout << str.find(str2) << endl;
    return 0;
}